Reference may be made to Australian Patent No. AU-A-15448/83 on Jatropha curcas oil for use with gasoline and diesel engines (assigned to Yuko Chemical Co. Ltd.). While this pioneering effort brought out the goodness of Jatropha oil, it is well known to those skilled in the art that raw oil is far too viscous to use in substantial proportions in modern day diesel engines.
Reference may be made to U.S. Pat. No. 6,399,800 by Haas et al. and US Patent Application No. 2004/0102640 A1 by Brunner et al. which disclose related methods of producing fatty acid alkyl esters through a combination of esterification and transesterification processes catalysed by acid and alkali, respectively. No mention is made of any of the inventions which are the subject matter of the present application.
Reference may also be made to German Patent Application No. DE 102,43,700 A1 wherein, methyl ester is obtained from a range of triglycerides including animal fat, using sulphuric acid and para-toluene sulphonic acid catalysts. No mention is made of the subject matter of the present application.
Reference may be made to the patent applications by Ghosh et al. (U.S. patent application Ser. No. 11/00239; PCT/IN04/00329 and accompanying national phase filings) wherein, an integrated process of production of Jatropha methyl ester from whole seed is disclosed integrated with recovery of by-products. The raw oil expelled from whole seed is neutralized with NaOH to reduce free fatty acid content and then transesterified with methanolic KOH with 5.0-5.5 mole of methanol per mole of triglyceride oil against the theoretical requirement of three moles of methanol per mole of triglyceride. The methyl ester is thereafter purified through washes with pure glycerol (4-5 kg per 100 kg of methyl ester) and thereafter washed with water to obtain product of >98% purity and satisfying all requirements as per EN14214 and ASTM specifications. The crude glycerol layer is subjected to distillation to recover methanol, then acidified to recover K2SO4 and soap-like matter, and thereafter subjected to distillation once again to recover glycerol in pure form, leaving behind a small amount of still bottom as waste. One drawback of the process is that not all of the oil is recovered in the form of methyl ester, a small portion being converted into soap which is formed in proportion to the free fatty acid content and, therefore, it is imperative that the free fatty acid content of the oil be maintained as low as possible. No mention is made of utilization of whole seed capsules as feedstock nor of any water less process of refining methyl ester nor of any process for production of polyhydroxyalkanoate from the crude glycerol.
Reference may be made to the article entitled “On Road Testing of Advanced Common Rail Diesel Vehicles with Biodiesel from the Jatropha curcas Plant” by S. Mandpe, S. Kadlaskar, W. Degen and S. Keppeler (2005-26-356, Proceedings of SAEINDIA Conference 2005) which narrates the performance of C-class Mercedes cars driven with the neat methyl ester prepared as per the process disclosed by Ghosh et al. in the reference cited above.
Reference may be made to the European project entitled “Local and Innovative Biodiesel” (Altener Contract No. 4.1030/C/02-022; http//www.fedarene.org/publications/projects/contract/biodiesel/home.htm; Coordinator—EREN; Report courtesy Austrian Biofuels Institute E.V.—Co-contractor), wherein, an evaluation was made of methyl esters from around the world prepared by different agencies using the same or different feedstocks. The Jatropha methyl ester (JME-05-728) prepared as per the process of the invention of Ghosh et al. (PCT/IN04/00329; U.S. patent application Ser. No. 11/00239) gave the best engine performance in terms of power derived, fuel consumption and long term performance.
Reference may be made to the article entitled “Biofuel—The little shrub that could—may be” by D. Fairless (Nature, 449, 2007, pp. 652-655) which narrates the promise that Jatropha curcas holds as a suitable source of biodiesel.
Reference may be made to the report of LEA Bioenergy Task 40 (http://www.city.northbay.on.ca/business/presentations/woodPellets/Global %20wood%20pellets%20market%20and%20industry%20Nov%2007%20report.pdf) which discusses at length the prospects of biomass pellets as fuel source and the desired specifications.
Reference may also be made to the article entitled “Prospects for Jatropha Methyl Ester (Biodiesel) in India” by Ghosh et al. (Int. J. Environ. Stud. (Taylor & Francis, U.K.)—special issue on India's future energy options; 2007, 64, pp 659-674) which states the possibility of making briquettes from whole seed capsules of Jatropha curcas after separation of seeds. There is, however, no mention of any process through which such briquettes are made nor of their specifications.
Reference may be made to the article entitled “Comparison of purification methods for biodiesel” by M. Berrios and R. L. Skelton (Chemical Engineering Journal, 2008, pp. 459-465) wherein different methods of purification of biodiesel are described. Specifically, a comparative assessment has been made of water washing, use of ion exchange resin, and use of magnesium silicate as adsorbent.
Reference may be made to German patent No. DE 43 01 686 C1 by Gross et al. which discloses a process of production of methyl ester of rape seed oil by a distillation process which makes it a water-less process.
Reference may be made to the article entitled “Refining of biodiesel by ceramic membrane separation” by Wang et al. (Fuel Processing Technology, Article in Press, 20 Dec. 2008) wherein ceramic membranes of the pore sizes of 0.6, 0.2 and 0.1 μm were used in an attempt to remove the residual soap and free glycerol through a water-less process.
Reference may be made to the web site of Purolite (http://www.desmoparts.com/filters/purolite/HBD-Purolite%20Regeneration.pdf) which mentions about resin PD206 [Purolite Application note/Purolite PD-206 Guide] which can be used in two ways: one for removing moisture, methanol and glycerol and the other for ion exchange of catalyst, salts and soaps exchanging primarily sodium (Na+) of the catalyst for hydrogen (H+) on the resin. It is reported that after adsorption of water, methanol, and glycerol from biodiesel the volume of resin expands to twice the dry volume of resin. Moreover, there is an estimated 10% attrition due to bead breakage in the first regeneration. Bead breakage and loss of functional groups are the limiting factors determining the number of times PD206 can be regenerated and there is presently a need to replace PD206 after 2-4 regenerations. Suffice it to say that use of resin would be viable only if the load of impurities in the methyl ester is at the barest minimum.
Reference may be made to U.S. Pat. No. 5,424,467 by Barn et al. wherein, the purification of methyl ester and utilization of crude glycerol layer are disclosed. It is stated therein that mono- and diglyceride impurities in the glycerol layer can be converted into the desired methyl ester through reaction with additional amounts of methanol. Methanol in the glycerol layer is recovered by distillation. No mention is made of recovery of methanol through the process of further reaction with triglyceride oil which is disclosed in the present invention.
Reference is once again made to the patent applications by Ghosh et al. (U.S. patent application Ser. No. 11/00239; PCT/IN04/00329) wherein an efficient method is provided that uses very small amounts of pure glycerol (ca. 3 kg per 100 kg of methyl ester) to wash the crude methyl ester which process minimizes residual impurities in the methyl ester while enriching them in the crude glycerol layer. As a result methanol recovery from methyl ester is not necessary while such recovery from glycerol layer is undertaken by distillation. The reported recovery of methanol is ca. 70-80% of the excess methanol used. No mention is made of any other possible methods of recovering methanol from the glycerol layer, nor any mention of making polyhydroxyalkanoates (PHAs) from the co-product streams.
Patent application No. WO/2006/084048 relates generally to bio-diesel fuels, and more particularly to a process for converting the waste glycerol generated by traditional transesterification processes into a miscible and combustible component of a bio-diesel fuel.
Reference may be made to the article entitled “From glycerol to value-added products” by M. Pagliaro et al. (Angew. Chem. Int. Ed. (2007), 46, 4434-4440) wherein, various products derived from glycerol, e.g. propylene glycol, 1,2-propanediol, soaps, drugs, explosives, detergents, cosmetics, dihydroxy-acetone (DHA), acrolein, epichlorohydrin, syngas-fuels, glycerol carbonate, anti-freezing agent, catalytic conversion to polymers, etc., are described. However, there is no reference to production of biopolymer (PHAs). Reference may be made to U.S. Pat. No. 7,388,034 by Goetsch et al. which discloses a method of producing methanol from the crude glycerol by-product of biodiesel process.
Reference may be made to “Biopolymers for Medical and Pharmaceutical Applications”, Vol. 1&2, A. Steinbüchel and R. H. Marchessault, Wiley-VCH Verlag GmbH & Co. KGaA (2005) and reference therein which cite numerous prior art pertaining to the preparation and properties of PHA. No reference is made to the approach to PHA production pertaining to the present invention.
Reference may be made to the paper by G. N. M. Huijberts et al. entitled “Pseudomonas putida KT2442 cultivated on glucose accumulates poly(3-hydroxyalkanoates) consisting of saturated and unsaturated monomers” (Applied and Environmental Microbiology, February 1992, Vol 58, Issue 2, pp 536-544) wherein growth of recombinant strain of Pseudomonas putida KT2442 was studied using different carbohydrates like glucose (2%), fructose (2%) and glycerol (4%) in E2 medium, producing PHA having similar monomer composition. The yield of PHA was 20.5% (w/w) with respect to cell dry weight.
Reference may be made to the paper by Taniguchi et al. entitled “Microbial production of poly(hydroxyalkanoate)s from waste edible oils” (Green Chem. 2003, 5, pp 545-548). The paper describes the results obtained with Ralstonia eutropha in a 2-stage fermentation process (one for growth of culture and the other for production of polyhydroxyalkanoate) which gave a maximum PHA yield of 83% with respect to cell dry weight when palm and lard were used. The production medium also contained inorganic nutrients/micronutrients while the growth medium contained nutrient broth which is costly.
Reference may be made to the research paper by R. D. Ashby et al. entitled “Bacterial poly(hydroxyalkanoate) polymer production from the biodiesel co-product stream.” (Journal of Polymers and the Environment, 2004, volume 12, pp 105-112) wherein, Pseudomonas oleovorans and Pseudomonas corrugata were used for PHA production from co-product stream of soya based biodiesel production (CSBP) stream containing glycerol, fatty acid soaps and residual fatty acid methyl esters at 1% to 5% concentration in a 2-stage fermentation process. The alkaline co-product stream (pH 13) was neutralized with 1 N HCl to pH 7 before using as substrate. The bacteria were initially grown in Luria-Bertani (LB) broth, which comprises several costly constituents including peptone and thereafter, the cells were transferred into the production medium containing the neutralized co-product stream and additional nutrients/micronutrients. The polymer cell productivity was only 42% of cell dry weight (CDW) with Pseudomonas corrugata while polymer yield with respect to glycerol was <5% even under optimized conditions. Such conditions include use of special media enriched in costly nutrients.
Reference may be made to the research paper by E. J. Bormann and M. Roth. entitled “The production of polyhydroxybutyrate by Methylobacterium rhodesianum and Ralstonia eutropha in media containing glycerol and casein hydrolysates” (Biotechnology Letters, 1999, Volume 21, pp 1059-1063) wherein the production of polyhydroxybutyrate (PHB) by these bacteria was in medium containing glycerol combined with casein peptone or casamino acids. The glycerol was used at a concentration of 2.5%, 5% and 7.5%. The yield of polymer was reported to be 17% (w/w) with respect to glycerol while, the polymer content as a percentage of cell dry weight was 39±6%.
Reference may be made to the research paper by Koller M., et al. entitled “Production of polyhydroxyalkanoates from agricultural waste and surplus materials” (Biomacromolecules, 2005, Volume 6, pp 561-565) wherein polyhydroxyalkanoate was obtained from whey hydrolysate (0.55%) and glycerol liquid phase (1.6%) supplemented with meat and bone meal by an osmophilic organism. The yield of PHA with respect to glycerol was 23% and the polymer had molecular weight of 253 kDa and melting endotherms at 128° C. and 139° C.
Reference may be made to the paper by Ito et al. (J. Bioscience & Bioengineering, 2005, 100, pp 260-265) which describes the biochemical production of hydrogen and ethanol from the glycerol-containing wastes discharged after biodiesel manufacturing process. It is reported that the biochemical activity is much lower than with pure glycerol due to the presence of high salt content in the wastes.
It will be evident from the prior art that no cost-effective process has been disclosed for production of PHA from biodiesel co-product streams and even with the use of costly co-nutrients and cumbersome 2-step process, the PHA yield with respect to cell dry weight is generally reported to be <50%. The prior art also teaches us that attempt to use glycerol-containing wastes led to much lower biochemical productivity than pure glycerol which is ascribed to the presence of high levels of salt. The present invention seeks to overcome all of these basic limitations and to evolve a novel, simplified and cost-effective process of producing PHA from glycerol co-product stream of methyl ester process starting from Jatropha whole seed capsule. Several other associated improvements in the process such as (i) best utilization of problematic waste, particularly oil sludge generated during mechanical expelling of oil and still bottom of glycerol distillation process, (ii) alternative solution to distillation of methanol from crude glycerol layer, and (iii) cost-effective resin treatment of glycerol-washed methyl ester also form part of the present invention.